High speed magnus rotor

ABSTRACT

A magnus rotor designed for high speed operation. Aerodynamic drag is reduced by lessening the air density around endplates and half the radial surface of the rotor by installing a circuit of aerodynamic seals to enclose a vacuum about the internal volume of the rotor as well as the endplates and half the radial surface of the rotor.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to magnus rotors and more specifically to the useof magnus rotors as part of a system for generating electricity fromwind energy.

2. Description of the Prior Art

It is generally accepted that a magnus rotor can only be revolved atabout four times the wind speed for the purpose of converting windenergy into electrical energy. Experiments have shown this to be correctwith the present technology. This is because as the magnus rotor is madeto spin faster and faster aerodynamic drag is built up rather rapidly tothe point where it takes more energy to revolve the rotor than theenergy output from the system. Referring to U.S. Pat. No. 4,582,013 andthe research upon which it is based as expressed in US Dept. of EnergyGrant Report #DOE/R6/10969 we see various attempts to reduce aerodynamicdrag. In FIG. 6 et alia of the patent we see the addition of a tailwhich is swung by the wind. This reduces turbulence downwind from therotor. In the Grant Report there is described a “Circulator” to reduceinduced drag. See page 16 of the report.

When the rotor is made to rotate, the top and bottom plates of the rotoralso rotate and cause the air next to them to swirl, causing aerodynamicdrag to be induced. The design of the “Circulator” imposes a mechanicalbarrier to prevent this circulation.

Also worth mentioning is the statement in U.S. Pat. No. 4,562,013 column28, lines 33-35 “Wind tunnel tests show major improvements inaerodynamic performance due to the presence of shield 9, and due toaerodynamic seals.” The structure of this shield is explained in col.28, lines 28-32.

SUMMARY OF THE INVENTION

Aerodynamic drag is directly dependant on the density of the atmosphere.Regardless of any other factor contributing to the increase inaerodynamic drag on a magnus rotor, reducing air density reducesaerodynamic drag. This reduction in the present invention isaccomplished by sealing off the upper and lower plates and the half ofthe cylinder being rotated against the wind current, by an aerodynamicseal. A vacuum is made over these surfaces which is maintained duringthe operation of the rotor. Also, the interior volume of the rotor isoriginally built with a vacuum.

It is the principal object of the invention to reduce aerodynamic dragon a magnus rotor.

The attainment of the foregoing and related objects, advantages andfeatures should be more readily apparent to those skilled in the artafter the review of the following more detailed description of theinvention, taken together with the drawing in which:

FIG. 1 is a perspective view of the invention.

DETAILED DESCRIPTION OF THE INVENTION

Turning to FIG. 1 we see magnus rotor 1 mounted on shaft 2 and operableby motor 3. Shield and tail 4 are made to enclose half the circularsurface and both endplates of rotor 1. Along the rim of each endplate ofrotor 1 is aerodynamic seal 5 a,b. Connecting these seals and locatedalong the leading and trailing edges of shield and tail 4 areaerodynamic seals 5 d,e. Extended from seal 5 d is pipe 6 filled withthe liquid of the seal which is operatively connected to reservoir 8.Likewise extended from seal 5 e is pipe 7 also operatively connected toreservoir 8. Fill tube 9 is extended from reservoir 8 to a surface oftail 4. Reservoir 8 is located within the volume of tail 4. Thus pipes5,6,7 form a network of pipes through which liquid may be made to flow.

In operation, as rotor 1 is made to spin liquid is urged from pipe 6 topipe 7. The liquid is made to maintain a vacuum next to the endplatesand half the radial surface of magnus rotor 1. Seals 5 c,f also are madeto maintain the vacuum of the interior volume of rotor 1. In this waythe rotor may be spun faster for the same power input by motor 3.Calculating the drag force by seal 5 on rotor 1 The coefficient ofkinetic friction of two oiled steel surfaces is 0.03-0.06. Assumingrotor 1 is rotated at a peripheral velocity of 1000 ft./sec. the normalforce on rotor 1 by seal 5 may approach 1 bar, depending on the designof seal 5. The torque exerted by rotor 1 on shaft 2 (which may besubstituted for a blade on a wind power turbine) is found by applyingthe Kutta-Joukowski formula.

From the above description it is apparent the embodiment achieves theprincipal object of the invention. The above embodiment is providedpurely as an example. Many other variations, modifications andapplications of this invention may be made. These are considered to beequivalent and within the spirit and scope of the invention.

I claim:
 1. A magnus rotor comprising: a. a cylinder with endplates,said endplates traversed by a shaft about which said rotor may berotated, b. a motor means operatively connected to said shaft, c. ashield means extended over said endplates and substantially half theradial wall, of said cylinder, d. an aerodynamic seal circuit envelopinga volume of a vacuum between said shield and said cylinder and extendedover the area of said shield so said vacuum is not lost, and e.aerodynamic seals about said shaft and located on said shield so avacuum within the interior of said cylinder is not lost, so when saidcylinder is made to turn aerodynamic drag on said cylinder is lessened.2. The magnus rotor of claim 1 wherein said shield is also formed as anaerodynamic tail means able to be rotated about said shaft soaerodynamic drag is further lessened about said cylinder in a wind. 3.The magnus rotor of claim 2 wherein said tail contains a reservoir ofsealing liquid to which both ends of said circuit are operativelyconnected.
 4. The aerodynamic tail means of claim 2 wherein said tailmeans defines a further volume of said vacuum. The magnus rotor of claim1 wherein said rotor and shaft replace a blade on a wind energyconversion system so electrical energy may be produced by the invention.